1. FIELD OF THE INVENTION
The present invention relates to a color photographic light-sensitive material, and more particularly it relates to a color photographic light-sensitive material capable of recording sound images.
2. DESCRIPTION OF THE PRIOR ART
As recording methods for sound images for color photographic light-sensitive materials, an optical recording system and a magnetic recording system are generally known. The present invention relates to the photographic materials suitable for the optical recording system.
Color print films, color reversal films, color reversal print films, etc. are used as the color photographic light-sensitive materials for movies and for television. Sound images are optically recorded with color images on the color photographic light-sensitive materials, and are reproduced by converting the sound signals recorded as the optical density or areas in the materials into light-signals, then converting the light-signals into electric signals using a light-receiving device, and further converting the electric signals into sound signals. In the reproduction steps of sound images, phototubes having various optical characteristics have been used as the light-receiving device. The most typical phototube which is called an "S-1 type" has an optical absorption maximum at about 800.mu. in the infra-red region (for example, as disclosed in Adrin Cornwell, Color Cinematography, page 593 (1951)).
On the contrary, color dyes, which are formed by the coupling reaction of color couplers and the oxidation products of color developing agents, such as the p-phenylenediamines, according to the subtractive color photography, all have a main absorption within the visible region, and therefore the main absorption of the dyes does not correspond to the optical characteristics of the above-described phototube. Accordingly, sound reproductions based on only color dye images are weak and impractical. For the purpose of more practical sound reproductions of color photographic light-sensitive materials, silver images or silver sulfide images are formed on the sound track areas of the color photographic light-sensitive materials in the developing process, and the optical density in the infra-red region of the images is utilized for sound reproductions. In this case, the optical density in the infra-red region (transmitting density) is usually about 1.0 to 1.6.
The sound track areas of color print films can be produced using the processing steps disclosed in the Journal of the Society of Motion Picture and Television Engineers, Vol. 77, page 1154 (1968). According to this method, color images of image portions and sound images of sound track areas are simultaneously developed in a color developing bath. In a first fixing bath, the unexposed silver halide is removed and in a bleaching bath, the developed silver formed in the developing step is rehalogenated. In a sound developing step, the silver halide corresponding to only the sound track areas is converted into silver images by coating a viscous sound developer on the sound track areas, selectively. In a second fixing bath, the silver halide in the image portions is removed, and in a stabilizing bath, the dye image are stabilized. Thus, the optical density in the infra-red region of the silver images on the sound track areas can be utilized for sound reproductions.
As described above, it is necessary in the production of the sound track areas of color films to form silver or silver sulfide images using processing steps other than the color image forming steps. The reason why the sound track areas containing silver or silver sulfide images is needed is due to the optical characteristics of the phototube used for the sound reproductions which requires an absorption maximum in the infra-red region and that the color dyes formed by color development do not have sufficient optical density in this region.
Color photographic light-sensitive materials capable of forming sound track areas which do not require the special processing steps as described above have been proposed (U.S. Pat. Nos. 3,705,801; 3,715,208; and 3,737,312; and U.S. patent application Ser. No. 360,507, filed May 15, 1973). The color photographic light-sensitive materials include an auxiliary layer capable of forming silver images upon color development and which are not bleached in a bleaching step. In the auxiliary layer, developable silver is hardly formed by imagewise exposure, but only in the sound track areas of the layer, silver for sound images is formed which is not bleached in the following bleaching step and hence remains in the layer. Therefore, photographic materials including the auxiliary layer have the advantage that the selective coating of a viscous sound developer on the sound track areas can be omitted. Further, with these photographic materials, since the silver images formed in the sound track areas by color development can be used as the sound images, the rehalogenation step of the developed silver is unnecessary, and the bleaching and fixing step can be carried out in the same bath, whereby the processing steps are simplified.
A color photographic light-sensitive material is composed of a support having coated thereon silver halide emulsion layers having different optical sensitivities. The photographic material is developed, after imagewise exposure, with a color developer, whereby color dye images and silver images are formed. Then, the material is bleached in a bleaching step, whereby the silver images are oxidized, and is fixed in a fixing step, whereby the silver halide is removed and a color photograph containing the color dye images can be obtained.
The above described color photographic light-sensitive material has a layer capable of forming silver images which are not removed by the bleaching and fixing steps, and gives, by conventional color development, a color photograph containing color dye images and silver images that are advantageously utilized as sound track areas.
As an advantageous method for forming the silver images which are not removed by the processing steps, the following compounds are proposed. That is, when the compound is incorporated into a silver halide emulsion layer, it remarkably reduces the rate at which silver is removed in the bleaching and fixing steps or it causes the silver to lose its ability to be removed in these steps. The compound can have the property in which the silver is removed in some degree only in the initial period of these steps but that the silver is not substantially removed after the initial period. Such a compound is defined as a bleach inhibitor in the specification.
As bleach inhibitors, a compound having a mercapto group is disclosed in Japanese Patent Application laid open to public inspection No. 13482/72. However, since a bleach inhibitor is also considered to be a development inhibitor or a chemical inhibitor, it is difficult to obtain a higher optical density of silver even if it is used. Namely, where a large amount of the bleach inhibitor is used, the amount of silver remaining after the bleaching step is small because the amount of the developed silver is small due to the development inhibitor while the bleach inhibiting effect is higher. On the other hand, where a small amount of the bleach inhibitor is used, the amount of silver remaining after the bleaching step is also small because the bleach inhibiting effect is lower while the amount of the developed silver is greater due to less development inhibition.
An object of the invention is, therefore, to provide a bleach inhibitor capable of providing sufficient optical density in the infra-red region without or with little development or chemical inhibition.
Another object of the invention is to provide a color photographic light-sensitive material capable of providing sufficient optical density in the infra-red region which does not require special processing steps as in the conventional method to produce sound track areas by using a novel bleach inhibitor.
Still another object of the invention is to provide a method for forming sound images having higher sound quality which does not involve special processing steps as in the conventional method.